1. Field of Invention
The present invention relates to a device and a method for controlling ISG logic, and more particularly, to a method of controlling ISG (Idle Stop & Go) logic of an ISG vehicle which automatically stops the engine in idling when the vehicle stops, and restarts the engine after a predetermined time to restart the vehicle.
2. Description of Related Art
The gases causing the greenhouse effect of the various gases in the atmosphere are called greenhouse gases. As the greenhouse gases, there are carbon dioxide, methane, nitrous oxide, Freon gas, and ozone. Although vapor is the most responsible for causing the natural greenhouse effect, a representative greenhouse gas causing global warming is carbon dioxide.
Since the latter half of 20th century, global warming has rapidly progressed, unusual weather such that localized heavy rain, drought, typhoon etc. has been rapidly increased. If the present level of contamination continues, it is expected that the greenhouse gas emissions throughout the world will reach a level that seriously threatens mankind and the ecosystem in the sooner future.
Therefore, international cooperation for reducing the exhaust amount of the greenhouse gases has been established to cope with global warming due to the greenhouse gases.
Various efforts have been made to reduce the greenhouse gases in the transportation field, and as a part of the efforts, a great deal of effort is made in improving fuel efficiency.
At the present time where the fuel efficiency is a central theme, use of an ISG (Idle Stop & Go) system is increasing over the world.
The ISG system gives an order to stop an engine in idling, on the basis of information on vehicle speed, the revolution speed of an engine, and the temperature of cooling water etc.
In other words, the ISG system is an engine control system that is provided with a function that automatically stops the idling engine when a vehicle stops for waiting the traffic lights in a town, and restarts (goes) the engine when starting the vehicle after a predetermined time to make normal operation possible.
The ISG system is also called an idling stop control device. The ISG system can achieve fuel effect of about 5˜15% in the actual fuel efficiency mode.
A vehicle equipped with the ISG system is called an ISG vehicle. Although the highest prior object of the ISG is to improve the fuel efficiency, forbidden conditions may be set by inclination conditions and battery conditions in order to improve safety and commercial value of the vehicle system.
Referring to FIG. 1, FIG. 1 is a flowchart illustrating a general process of idle stop & go of an ISG vehicle equipped with an automatic transmission.
A common ISG vehicle with an automatic transmission should be equipped with a transmission sub-oil pump to implement the ISG system and the transmission sub-oil pump is used to keep the hydraulic pressure of the transmission when the engine stops.
In the vehicle provided with the ISG system by being equipped with the transmission sub-oil pump, the engine is stopped (S130), when the brake pedal is pressed down to stop the vehicle at the D-range (“Yes” in S110) while an idle stop entrance condition is determined (S100). In this process, the sub-oil pump operates to keep the hydraulic pressure of the transmission.
That is, the condition for stopping the engine by the ISG system is that the vehicle stops with the vehicle speed not detected, the gear is held at the D-range, and the brake pedal is operated and kept at a predetermined time, in which the engine is stopped to increase the fuel efficiency.
Thereafter, when the brake pedal is released at the D-range, with the vehicle stopped (“Yes” in S150), the engine is automatically restarted (S170). In this state, the transmission sub-oil pump is turned off.
That is, with the engine stopped by the ISG system, when the user's intention of starting the vehicle, such as releasing the brake pedal and operating the acceleration pedal, is detected, the engine is turned on to maintain normal traveling.
In the ISG vehicle equipped with an automatic transmission, when the brake pedal is pressed down while the vehicle travels, with the gear at the D-range, the engine stops, and when the brake pedal is released at the D-range, the engine is automatically restarted.
Unlike the engine is restarted at the P-range or the N-range in the related art, since the engine is started, with the driving system and the power system connected, engine increase RPM overshoot is transmitted to the driving system with the restart, the vehicle moves forward.
That is, referring to FIGS. 2 and 3, FIG. 2 is a diagram showing when the engine is restarted at the P-range or the N-range and FIG. 3 is a diagram showing when the engine is restarted at the D-range.
As shown in FIG. 2, when the engine is restarted at the P-range or the N-range in the related art, since the driving system and the power system are not connected, although the vehicle body is vibrated when the engine is restarted, as shown in FIG. 3, when the engine is restarted at the D-range, engine RPM increase torque is transmitted to the driving system when the engine is restarted, starting acceleration is generated and the vehicle moves forward.
Such a problem should be removed in developing an ISG vehicle equipped with an automatic transmission.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.